Dronedarone-Induced Cardiac Mitochondrial Dysfunction and Its Mitigation by Epoxyeicosatrienoic Acids

Amiodarone but not propafenone impairs bioenergetics and autophagy of human myocardial cells

Cardiac and extra-cardiac side effects of common antiarrhythmic agents might be related to drug-induced mitochondrial dysfunction. Supratherapeutic doses of amiodarone have been shown to impair mitochondria in animal studies, whilst influence of propafenone on cellular bioenergetics is unknown. We aimed to assess effects of protracted exposure to pharmacologically relevant doses of amiodarone and propafenone on cellular bioenergetics and mitochondrial biology of human and mouse cardiomyocytes. In this study, HL-1 mouse atrial cardiomyocytes and primary human cardiomyocytes derived from the ventricles of the adult heart were exposed to 2 and 7 μg/mL of either amiodarone or propafenone. After 24 h, extracellular flux analysis and confocal laser scanning microscopy were used to measure mitochondrial functions. Autophagy was assessed by western blots and live-cell imaging of lysosomes. In human cardiomyocytes, amiodarone significantly reduced mitochondrial membrane potential and ATP production, in association with an inhibition of fatty acid oxidation and impaired complex I- and II-linked respiration in the electron transport chain. Expectedly, this led to increased anaerobic glycolysis. Amiodarone increased the production of reactive oxygen species and autophagy was also markedly affected. In contrast, propafenone-exposed cardiomyocytes did not exert any impairment of cellular bioenergetics. Similar changes after amiodarone treatment were observed during identical experiments performed on HL-1 mouse cardiomyocytes, suggesting a comparable pharmacodynamics of amiodarone among mammalian species. In conclusion, amiodarone but not propafenone in near-therapeutic concentrations causes a pattern of mitochondrial dysfunction with affected autophagy and metabolic switch from oxidative metabolism to anaerobic glycolysis in human cardiomyocytes.

Mitochondrial Effects of Common Cardiovascular Medications: The Good, the Bad and the Mixed

Mitochondria are central organelles in the homeostasis of the cardiovascular system via the integration of several physiological processes, such as ATP generation via oxidative phosphorylation, synthesis/exchange of metabolites, calcium sequestration, reactive oxygen species (ROS) production/buffering and control of cellular survival/death. Mitochondrial impairment has been widely recognized as a central pathomechanism of almost all cardiovascular diseases, rendering these organelles important therapeutic targets. Mitochondrial dysfunction has been reported to occur in the setting of drug-induced toxicity in several tissues and organs, including the heart. Members of the drug classes currently used in the therapeutics of cardiovascular pathologies have been reported to both support and undermine mitochondrial function. For the latter case, mitochondrial toxicity is the consequence of drug interference (direct or off-target effects) with mitochondrial respiration/energy conversion, DNA replication, ROS production and detoxification, cell death signaling and mitochondrial dynamics. The present narrative review aims to summarize the beneficial and deleterious mitochondrial effects of common cardiovascular medications as described in various experimental models and identify those for which evidence for both types of effects is available in the literature.

Cardiomyocyte-specific CYP2J2 and its therapeutic implications

INTRODUCTION

Cytochrome P450s (CYPs) are a superfamily of monooxygenases with diverse biological roles. CYP2J2 is an isozyme highly expressed in the heart where it metabolizes endogenous substrates such as N-3/N-6 polyunsaturated fatty acids (PUFA) to produce lipid mediators involved in homeostasis and cardioprotective responses. Expanding our knowledge of the role CYP2J2 has within the heart is important for understanding its impact on cardiac health and disease.

AREAS COVERED

The objective of this review was to assess the state of knowledge regarding cardiac CYP2J2. A literature search was conducted using PubMed-MEDLINE (from 2022 and earlier) to evaluate relevant studies regarding CYP2J2 mediated cardioprotection, small molecule modulators, effects of CYP2J2 substrates toward biologically relevant effects and implications of CYP2J2 polymorphisms and sexual dimorphism in the heart.

EXPERT OPINION

Cardiac CYP2J2-mediated metabolism of endogenous and exogenous substrates have been shown to impact cardiac function. Identifying individual factors, like sex and age, that affect CYP2J2 require further elucidation to better understand CYP2J2's clinical relevance. Resolving the biological targets and activities of CYP2J2-derived PUFA metabolites will be necessary to safely target CYP2J2 and design novel analogues. Targeting CYP2J2 for therapeutic aims offers a potential novel approach to regulating cardiac homeostasis, drug metabolism and cardioprotection.

Assessing Drug-Induced Mitochondrial Toxicity in Cardiomyocytes: Implications for Preclinical Cardiac Safety Evaluation

Drug-induced cardiotoxicity not only leads to the attrition of drugs during development, but also contributes to the high morbidity and mortality rates of cardiovascular diseases. Comprehensive testing for proarrhythmic risks of drugs has been applied in preclinical cardiac safety assessment for over 15 years. However, other mechanisms of cardiac toxicity have not received such attention. Of them, mitochondrial impairment is a common form of cardiotoxicity and is known to account for over half of cardiovascular adverse-event-related black box warnings imposed by the U.S. Food and Drug Administration. Although it has been studied in great depth, mitochondrial toxicity assessment has not yet been incorporated into routine safety tests for cardiotoxicity at the preclinical stage. This review discusses the main characteristics of mitochondria in cardiomyocytes, drug-induced mitochondrial toxicities, and high-throughput screening strategies for cardiomyocytes, as well as their proposed integration into preclinical safety pharmacology. We emphasize the advantages of using adult human primary cardiomyocytes for the evaluation of mitochondrial morphology and function, and the need for a novel cardiac safety testing platform integrating mitochondrial toxicity and proarrhythmic risk assessments in cardiac safety evaluation.

Rational deuteration of dronedarone attenuates its toxicity in human hepatic HepG2 cells

Deuteration is a chemical modification strategy that has recently gained traction in drug development. The replacement of one or more hydrogen atom(s) in a drug molecule with its heavier stable isotope deuterium can enhance its metabolic stability and pharmacokinetic properties. However, it remains uninterrogated if rational deuteration at bioactivation "hot-spots" could attenuate its associated toxicological consequences. Here, our preliminary screening with benzofuran antiarrhythmic agents first revealed that dronedarone and its major metabolite N-desbutyldronedarone elicited a greater loss of viability and cytotoxicity in human hepatoma G2 (HepG2) cells as compared with amiodarone and its corresponding metabolite N-desethylamiodarone. A comparison of dronedarone and its in-house synthesized deuterated analogue (termed poyendarone) demonstrated that deuteration could attenuate its in vitro toxicity in HepG2 cells by modulating the extent of mitochondrial dysfunction, reducing the dissipation of mitochondrial membrane potential, and evoking a distinct apoptotic kinetic signature. Furthermore, although pretreatment with the CYP3A inducer rifampicin or the substitution of glucose with galactose in the growth media significantly augmented the loss of cell viability elicited by dronedarone and poyendarone, a lower loss of cell viability was consistently observed in poyendarone across all concentrations. Taken together, our preliminary investigations suggested that the rational deuteration of dronedarone at its benzofuran ring reduces aberrant cytochrome P450 3A4/5-mediated bioactivation, which attenuated its mitochondrial toxicity in human hepatic HepG2 cells.

Site-directed deuteration of dronedarone preserves cytochrome P4502J2 activity and mitigates its cardiac adverse effects in canine arrhythmic hearts

Cytochrome P4502J2 (CYP2J2) metabolizes arachidonic acid (AA) to cardioprotective epoxyeicosatrienoic acids (EETs). Dronedarone, an antiarrhythmic drug prescribed for treatment of atrial fibrillation (AF) induces cardiac adverse effects (AEs) with poorly understood mechanisms. We previously demonstrated that dronedarone inactivates CYP2J2 potently and irreversibly, disrupts AA-EET pathway leading to cardiac mitochondrial toxicity rescuable via EET enrichment. In this study, we investigated if mitigation of CYP2J2 inhibition prevents dronedarone-induced cardiac AEs. We first synthesized a deuterated analogue of dronedarone (termed poyendarone) and demonstrated that it neither inactivates CYP2J2, disrupts AA-EETs metabolism nor causes cardiac mitochondrial toxicity in vitro. Our patch-clamp experiments demonstrated that pharmacoelectrophysiology of dronedarone is unaffected by deuteration. Next, we show that dronedarone treatment or CYP2J2 knockdown in spontaneously beating cardiomyocytes indicative of depleted CYP2J2 activity exacerbates beat-to-beat (BTB) variability reflective of proarrhythmic phenotype. In contrast, poyendarone treatment yields significantly lower BTB variability compared to dronedarone in cardiomyocytes indicative of preserved CYP2J2 activity. Importantly, poyendarone and dronedarone display similar antiarrhythmic properties in the canine model of persistent AF, while poyendarone substantially reduces beat-to-beat variability of repolarization duration suggestive of diminished proarrhythmic risk. Our findings prove that deuteration of dronedarone prevents CYP2J2 inactivation and mitigates dronedarone-induced cardiac AEs.

Cell-Permeable Succinate Rescues Mitochondrial Respiration in Cellular Models of Amiodarone Toxicity

Amiodarone is a potent antiarrhythmic drug and displays substantial liver toxicity in humans. It has previously been demonstrated that amiodarone and its metabolite (desethylamiodarone, DEA) can inhibit mitochondrial function, particularly complexes I (CI) and II (CII) of the electron transport system in various animal tissues and cell types. The present study, performed in human peripheral blood cells, and one liver-derived human cell line, is primarily aimed at assessing the concentration-dependent effects of these drugs on mitochondrial function (respiration and cellular ATP levels). Furthermore, we explore the efficacy of a novel cell-permeable succinate prodrug in alleviating the drug-induced acute mitochondrial dysfunction. Amiodarone and DEA elicit a concentration-dependent impairment of mitochondrial respiration in both intact and permeabilized platelets via the inhibition of both CI- and CII-supported respiration. The inhibitory effect seen in human platelets is also confirmed in mononuclear cells (PBMCs) and HepG2 cells. Additionally, amiodarone elicits a severe concentration-dependent ATP depletion in PBMCs, which cannot be explained solely by mitochondrial inhibition. The succinate prodrug NV118 alleviates the respiratory deficit in platelets and HepG2 cells acutely exposed to amiodarone. In conclusion, amiodarone severely inhibits metabolism in primary human mitochondria, which can be counteracted by increasing mitochondrial function using intracellular delivery of succinate.

Yellow Wine Polyphenolic Compound Protects Against Doxorubicin-Induced Cardiotoxicity by Modulating the Composition and Metabolic Function of the Gut Microbiota

BACKGROUND

Dietary polyphenols help to prevent cardiovascular diseases, and interactions between polyphenols and gut microbiota are known to exist. In this study, we speculated that gut microbiota-mediated metabolite regulation might contribute to the anticardiotoxic effects of yellow wine polyphenolic compound (YWPC) in doxorubicin (DOX)-treated rats.

METHODS

16S-rDNA sequencing was performed to analyze the effects of YWPC on the gut microbiota in DOX-treated rats (n=6). Antibiotics were used to investigate the contribution of the altered microbiome to the role of YWPC (n=6). Plasma metabolomics were also analyzed by untargeted gas chromatography-mass spectrometry systems.

RESULTS

YWPC ameliorated DOX-mediated cardiotoxicity, as evidenced by increased cardiac and mitochondrial function and reduced levels of inflammation and myocardial apoptosis (P<0.05 for all). The low abundance of Escherichia-Shigella, Dubosiella, and Allobaculum, along with enrichment of Muribaculaceae_unclassified, Ralstonia, and Rikenellaceae_RC9_gut_group in the gut, suggested that YWPC ameliorated DOX-induced microbial dysbiosis. YWPC also influenced the levels of metabolites altered by DOX, resulting in lower arachidonic acid and linoleic acid metabolism and higher tryptophan metabolite levels (P<0.05 for all). Correlational studies indicated that YWPC alleviated DOX-induced inflammation and mitochondrial dysfunction by modulating the gut microbial community and its associated metabolites. Antibiotic treatment exacerbated cardiotoxicity in DOX-treated rats, and its effect on the gut microbiota partly abolished the anticardiotoxic effects of YWPC, suggesting that the microbiota is required for the cardioprotective role of YWPC.

CONCLUSIONS

YWPC protected against DOX-induced cardiotoxicity in a gut microbiota-dependent manner. This supports the use of dietary polyphenols as a therapeutic approach for the treatment of cardiovascular diseases via microbiota regulation.

Development of Robust 17(R),18(S)-Epoxyeicosatetraenoic Acid (17,18-EEQ) Analogues as Potential Clinical Antiarrhythmic Agents

17(R),18(S)-Epoxyeicosatetraenoic acid (EEQ) is a cytochrome P450 metabolite of eicosapentaenoic acid (EPA) and a powerful negative chronotrope with low nanomolar activity in a neonatal rat cardiomyocyte (NRCM) arrhythmia model. Prior studies identified oxamide 2b as a soluble epoxide hydrolase (sEH) stable replacement but unsuitable for in vivo applications due to limited oral bioavailability and metabolic stability. These ADME limitations have been addressed in an improved generation of negative chronotropes, e.g., 4 and 16, which were evaluated as potential clinical candidates.